Inside the $1.5B Bybit Hack: How Lazarus Pulled Off the Largest Crypto Heist Ever
On April 11, 2025, the Web3 world watched in disbelief as Bybit, one of the most trusted centralized crypto exchanges, disclosed a $1.5 billion exploit—the single largest crypto heist in history. While major exchanges have been targeted before, the speed, sophistication, and scale of this attack sent shockwaves across the blockchain ecosystem.
"The Bybit hack isn't just a breach—it's a geopolitical event wrapped in smart contract code."
Here’s a detailed breakdown of what happened, who’s behind it, and how Web3 security must evolve.
What Happened?
The attackers exploited a subtle flaw in the user interface logic between Bybit’s multisig infrastructure and a wallet integration powered by Safe{Wallet}. The front-end misleadingly displayed the correct destination address to the user while the signed transaction silently redirected funds to an attacker-controlled wallet.
Within minutes, over 13,000 ETH, 340 million USDT, and other assets were drained. The hacker used a complex laundering path involving THORChain, cross-chain bridges, and Sinbad mixer (a Tornado Cash alternative).
Who Was Behind It?
Blockchain forensics firms like Elliptic and ChainArgus traced the funds to wallets previously associated with Lazarus Group, North Korea’s state-sponsored cybercrime unit. Their track record includes Ronin Bridge and Harmony hacks, making this their most lucrative operation to date.
Analysts believe Lazarus employed a mix of social engineering and UI-based deception to get Bybit staff to approve seemingly legitimate withdrawals.
The Attack Flow
- Hackers compromised 3/6 multisignature wallets required to send transaction
- Exploit triggered during internal asset rotation process
- UI spoof displayed trusted address, but TX signed pointed elsewhere
- Fast laundering via THORChain and Sinbad mixer
- Bridge-swapped assets into Monero and off-ramped through OTC desks
It’s a textbook example of how interface-layer assumptions can become billion-dollar mistakes.
Bybit's Response
To their credit, Bybit’s crisis response was swift and transparent:
- Withdrawals paused platform-wide within 14 minutes
- Internal audit and chain analysis teams deployed
- Full reimbursement of affected funds from treasury
- 10% white-hat bounty offered for return of stolen assets
"We're rebuilding Bybit's infrastructure with Zero Trust principles in mind." — Ben Zhou, CEO
What This Means for Web3 Security
The exploit raises serious red flags for any project relying on signature aggregation, off-chain interfaces, or multi-sig wallet tools. It’s a stark reminder that:
- Trusted UIs are not tamper-proof
- Cosigning platforms need independent verification layers
- Hardware wallets are not immune to social engineering
Final Thoughts
The Bybit breach may mark a turning point for crypto ops security. Just as the Mt. Gox hack shaped early Bitcoin security culture, this event could redefine the next wave of custodial and wallet design standards.
At Security4Web3, we’re already helping clients adapt with simulation frameworks, adversarial wallet testing, and UI signature spoof detection. If you're managing any custodial flows, get in touch. Because the Lazarus Group isn’t done.
Talk to our security engineers before they do.